Abstract
Effects of alloying elements, microstructure and applied stress on temper embrittlement were studied at standpoints of the saturated amount and the rate of embrittlement in low pressure turbine rotor steels. The saturated amount of temper embrittlement was increased by Si or Mn content. It was affected by microstructure, but was not affected by hardness after tempering and applied stress. The saturated amount of temper embrittlement was the largest in a sample with martensite. The next was in a sample with bainite and the smallest in a sample with pearlite. The rate of temper embrittlement was enhanced by an increase in Mn content or hardness or by tensile stress. It was prevented by hydrostatic compression. Si and microstructure did not influence the rate of temper embrittlement. The amount of temper embrittlement increased with the amount of phosphorus segregated to grain boundary in samples with a certain microstructure. The amount of embrittlement was larger in samples with high hardness than in samples with low hardness at a certain amount of phosphorus segregated.
